In the operation of a stabilized orbiting satellite there is always a need to control or limit uncontrolled tumbling of the spacecraft. Such uncontrolled motion of a satellite, intended to be stabilized in orbit, renders the satellite effectively useless for its planned operation. Furthermore, prolonged tumbling at excessive angular momentum may jeopardize the structural integrity of the spacecraft as well as the spacecraft's thermal and power balance. Therefore, it is desirable that recovery of the satellite occur within a short period of time after tumbling begins.
Control of tumbling can be accomplished by mass expulsion devices such as, rocket thrusters or jets. The use of such devices to control or limit spacecraft tumbling often requires excessive propellant usage. In the situation where no propellant is available, such means cannot be used to stabilize the spacecraft. Where electrical power in the satellite is available, it is more desirable to control tumbling by changing the spacecraft's spin rate by an autonomous control system.
Magnetic torquing of stabilized satellites, in particular for changing the attitude of a spacecraft that has deviated from its desired orientation relative to its orbit, is known. Such magnetic torquing systems use a magnetic field from torquers such as coils or electromagnets to interact with the magnetic field of the earth to develop a reaction torque. This reaction torque causes the reference axis of the satellite to be reoriented an amount proportional to the torquing time and flux magnitude. Magnetic torquing can also be used to develop a reaction torque to control the spin rate and the angular momentum of a spacecraft. These known magnetic torquing systems may be implemented in a satellite or spacecraft with an automatic (e.g., closed-loop) control system or an open-loop control system requiring command signals from a ground-situated station.
Most electronic devices experience changes in operating characteristics based on their operating temperature. For most applications, these variations are slight and can either be ignored or compensated for through calibration. However, there are instances in which environmental temperature regulation is required to ensure proper operation of an electronic device. For example, in many space applications where unregulated temperatures would be extremely cold, environmental temperature regulation is required. At these extreme temperatures, electronic components may have operating characteristics that are quite different from their operating characteristics at room temperature causing them to malfunction or provide erroneous readings. Further, temperature regulation is also typically required for components of any sort that are particularly sensitive to variations in temperature.
In many applications, strip heaters are used in temperature control systems for providing heat to electronic devices. Strip heaters include a resistive element that generates heat when a current is applied thereto. The heating element is typically either an elongated wire or trace of resistive material deposited on a substrate. The heating element is typically arranged in a pattern over a defined area to provide uniform heat over the defined area. When current is applied to the heating element, heat is emitted from the strip heater.
While strip heaters are considered an inexpensive and efficient means of providing heat to electronic devices for environmental temperature control, there are some drawbacks to these devices. Specifically, in spacecraft applications strip heaters add mass to the overall system. Minimizing the mass of a spacecraft is key to controlling the high launch expense.
In addition to heaters, satellites and other mobile platforms typically include separate degaussing coils for minimizing residual magnetism in equipment on the device. Having separate devices for magnetic flux generation, heating and degaussing adds complexity and mass to the mobile platform.
Therefore, it would be desirable to have a method and device that provides for magnetic flux generation, heating and degaussing that is less complex and requires less mass than those systems utilizing separate devices for some or all of these three functions.